In order to reduce CO2 emission from the viewpoint of global environment conservation, improving the fuel efficiency of an automobile by reducing the weight of the automobile body while maintaining the strength of the automobile body continues to be an important issue in the automobile industry. In order to reduce the weight of an automobile body while maintaining the strength of the automobile body, reducing the thickness of a steel sheet by increasing the strength of the steel sheet which is used as a material for automobile parts is effective. Here, many automobile parts which are made from a steel sheet are formed by using, for example, a press forming method or a burring forming method. Therefore, a high-strength galvanized steel sheet which is used as a material for automobile parts is required to have not only a desired strength but also excellent formability.
Nowadays, there is a growing trend toward using a high-strength galvanized steel sheet as a material for the skeleton of an automobile body. When a high-strength galvanized steel sheet is formed, since work which mainly involves bending is performed in many cases, excellent bending workability is required. In addition, since the combination of work which mainly involves bending and stretch flange forming significantly increases applicability to automobile parts, there is a demand for a material having both satisfactory bending workability and satisfactory stretch flange formability. Against such a background, various high-strength galvanized steel sheets excellent in terms of bending workability and stretch flange formability are being developed. Patent Literature 1 and Patent Literature 2 disclose techniques regarding high-strength galvanized steel sheets excellent in terms of bending workability from the viewpoint of cracking. Patent Literature 3 discloses a technique regarding a high-strength galvanized steel sheet excellent in terms of stretch flange formability.